package com.ltl.project.upload_server.servlet;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.lang.reflect.Method;

/**
 * 通过继承 HttpServlet 实现自己的 Servlet
 */
public abstract class BaseServlet extends HttpServlet {

    /**
     * 内部执行 doPost
     *
     * @param req
     * @param resp
     * @throws ServletException
     * @throws IOException
     */
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doPost(req, resp);
    }

    /**
     * 真正处理请求的方法
     *
     * @param req
     * @param resp
     * @throws ServletException
     * @throws IOException
     */
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        // 解决post请求中文乱码问题
        // 一定要在获取请求参数之前调用才有效
        req.setCharacterEncoding("UTF-8");

        // 获取 action 参数，获知要执行的业务
        String action = req.getParameter("action");
        try {
            // 获取action业务鉴别字符串，获取相应的业务 方法反射对象
            Method method = this.getClass().getDeclaredMethod(action, HttpServletRequest.class, HttpServletResponse.class);
            // 调用目标业务 方法
            method.invoke(this, req, resp);
        } catch (Exception e) {
            e.printStackTrace();
            // 把异常抛给Filter过滤器
            throw new RuntimeException(e);
        }
    }
}
